The first skeletal record of the enigmatic Cretaceous sawfish genus Ptychotrygon (Chondrichthyes, Batoidea) from the Turonian of Morocco

Abstract

A new fossil batoid (ray) Ptychotrygon rostrispatula sp. nov. is described from five exceptionally well‐preserved, three‐dimensional skeletal remains from the Turonian (Late Cretaceous) of Morocco. These specimens represent the first known skeletal remains for the genus Ptychotrygon and allow an almost complete description of the genus, providing a new insight into its phylogenetic relations and validating its taxonomic status as a member of the Sclerorhynchoidei. Mechanical preparation of the fossil remains revealed a relatively large batoid species (estimated total length above 1 m). Overall the morphology resembles that of sclerorhynchoids, with a robust hypertrophied rostrum that lacks enlarged rostral denticles with enlarged paddle‐like pectoral proximal elements (propterygium, mesopterygium and metapterygium). Never before seen details of the branchial skeleton are presented (large second hypobranchial without anterior process, which was probably fused to the basibranchial and no evidence of articulation with other branchial element). To assess the phylogenetic relations of these specimens within the sclerorhynchoids a parsimonious analysis using TNT and PAUP was performed. These analyses included Asflapristis cristadentis and Ptychotrygon rostrispatula sp. nov., which were used as representatives of Ptychotrygonidae, and also includes six other genera of sclerorhynchoids with relatively good skeletal remains. Both analyses recovered two monophyletic groups within sclerorhynchoids: the first contains Ischyrhiza, Onchopristis and Schizorhiza, and a second that includes Micropristis, Sclerorhynchus, Libanopristis and Ptychotrygonidae.

The skeletal remains of the euryhaline sclerorhynchoid †Onchopristis(Elasmobranchii) from the ‘Mid’-Cretaceous and their palaeontological implications

“…17 C). The character matrix for the phylogenetic analysis used here is a modified version from that used by Villalobos et al (2019b). The main changes include recoding of the polymorphic characters 5, 6 and 9, which were changed for Raja and Amblyraja (see supplement material;…”

Peer Review #1 of "Returning to the roots: resolution, reproducibility, and robusticity in the phylogenetic inference of Dissorophidae (Amphibia: Temnospondyli) (v0.1)"

“…A recent comparison of performance of different parsimony programs on phylogenomic data by Goloboff, Catalano & Torres (2021) noted that PAUP* recovered optimal trees in all datasets but one compared to TNT. Other paleontological studies have recovered the same number and length of MPTs between programs, both with large numbers of MPTs (e.g., Spaulding, O'Leary & Gatesy, 2009;Ford & Benson, 2020) and with small numbers of MPTs (e.g., Davesne et al, 2016;Villalobos-Segura, Underwood & Ward, 2021). Most studies do not report the majority of employed parameters, so while it can be reasonably assumed that most studies use the default settings (with various differences between TNT and PAUP*, e.g., branch-collapsing rule, TBR reconnection limit), this is not actually known.…”

A new cuspidate ptychodontid shark (Chondrichthyes; Elasmobranchii), from the Upper Cretaceous of Morocco with comments on tooth functionalities and replacement patterns

“…2 ), searching for macrofossils, such as exceptionally preserved vertebrate remains usually embedded in calcareous nodules (e.g. Bardet et al, 2003a , b ; Cavin et al, 2010 ; Claeson et al, 2013 ; Angst and Bardet, 2015 ; Allemand et al, 2018 ; Cooper and Martill, 2020 ; Villalobos-Segura et al, 2021 ). In particular, a sequence of alternating facies succession consisting of fossiliferous packstones, chalky marls, cherts and vertebrate-bearing nodular horizons belonging to the Asfla Member ( Fig.…”

“…mosasauroids and plesiosaurs) and, more rarely, elasmobranchs (e.g. Bardet et al, 2003a , b ; Kennedy et al, 2008 ; Cavin et al, 2010 ; Claeson et al, 2013 ; Angst and Bardet, 2015 ; Gale et al, 2017 ; Meister et al, 2017 ; Allemand et al, 2018 ; Villalobos-Segura et al, 2019 , 2021 ; Cooper and Martill, 2020 ). Additionally, the limestones of the Akrabou Fm include shell beds, with a low-diversified bivalve assemblage, and stromatolites in various horizons ( Kennedy et al, 2008 ; Cooper and Martill, 2020 ).…”

“…In this area, the shape and size of the nodules can greatly vary, sometimes completely embedding the fossil remains or only partially incorporating them. Additionally, fossils from this region also might be contained in more or less continuous limestone layers in certain levels ( L. Cavin, pers. comm.…”